Explain the principles and applications of volu... - SS3 Chemistry Analytical Chemistry II: Quantitative Analysis Question

Principles and Applications of Volumetric Analysis using Titration Techniques:

Volumetric analysis, also known as titration, is a quantitative analytical technique used to determine the concentration of a substance (analyte) in a sample by reacting it with a standardised solution (titrant) of known concentration. The principles of titration are based on stoichiometry, where the reactants react in specific mole ratios, allowing for precise determination of the analyte's concentration. Titration is widely used in various industries and research fields due to its accuracy, simplicity, and versatility.

Different Types of Titrations and their Indicators:

1.    Acid-Base Titrations: In acid-base titrations, a strong acid reacts with a strong base or vice versa. The endpoint of the titration is determined using indicators such as phenolphthalein, methyl orange, or bromothymol blue, which change colour at specific pH ranges.

2.    Redox Titrations: Redox titrations involve the transfer of electrons between the analyte and the titrant. Common indicators for redox titrations include potassium dichromate (K₂Cr₂O₇) and potassium permanganate (KMnO₄), which change colour upon completion of the redox reaction.

3.    Complexometric Titrations: Complexometric titrations involve the formation of complex ions between the analyte and the titrant. The most commonly used indicator in complexometric titrations is Eriochrome Black T, which changes colour at a specific pH range.

Examples of Titration Applications:

●     Determination of the concentration of hydrochloric acid (HCl) in a laboratory sample using a standardised sodium hydroxide (NaOH) solution in an acid-base titration with phenolphthalein as the indicator.

●     Estimation of the amount of iron (Fe²⁺) in a sample using a standardised potassium dichromate (K₂Cr₂O₇) solution in a redox titration with diphenylamine-sulfuric acid as the indicator.

●     Quantification of calcium (Ca²⁺) in a water sample using a standardised ethylenediaminetetraacetic acid (EDTA) solution in a complexometric titration with Eriochrome Black T as the indicator.